The present invention pertains generally to rivet type fasteners for attachment in holes of work pieces; and more particularly, to self-locking rivet type fasteners that can be released for removal and re-use.
Various types of push-in fasteners have been used for engagement in holes of work pieces, to fasten together adjacent panels, or secure objects on the work piece. In a simple form for such a fastener, the work piece is provided with a hole. The fastener includes a head and a shank. The head is sized larger than the hole, so that the head will not pass into or through the hole. The shank includes outwardly biased but yieldable segments, frequently having an inwardly angled tapered tip. The expanded portion of the shank is nominally larger than the hole. Securing the fastener in the work piece is achieved by forcing the shank into the hole. As the shank enters and slides through the hole, the outwardly biased yet yieldable portions move slightly inwardly to allow full insertion of the fastener, until the head engages a surface of the work piece first entered by the fastener. A segment of the shank extends through the hole in the work piece. Due to the shape of the shank and the structure of the shank segments controlling the degree to which each can yield or deflect, withdrawal of the shank from the aligned apertures can be made difficult or prevented. A disadvantage of this type of fastener is that the insertion pressure required to cause the shank segments to yield may be disadvantageously high if the outward biasing force of the segments is sufficient to inhibit or prevent subsequent withdrawal of the fully inserted fastener.
In another type of fastener, the shank includes a hollow core accessed through an opening in the head. A pin is provided. After the shank has been fully inserted, the pin is driven into the core of the shank, thereby urging the shank outwardly and securing the fastener in the hole of the work piece. Two-part fasteners of this type have disadvantages in that the parts can become separated from each other. Proper insertion of the pin into the shank may be troublesome if the access area is limited, or the individual using the fastener does not have sufficient dexterity to handle significantly small pins.
A fastener with a retained movable pin is shown in U.S. Pat. No. 6,074,144. A disadvantage of this design is that multiple steps are required to pre-assemble the fastener before actual use. The pin must be positioned in a pre-locking position after initial molding of the fastener.
Similar structures can be used as a fastening base or anchor on the surface of a work piece, rather than as a fastener joining two work pieces. The fastener is inserted in a work piece, and carries a superstructure on the surface of the work piece. The superstructure is configured for the attachment thereto of another work piece, covering or the like. It would be advantageous in many such applications if the fastener were easily removable and reusable.
What is needed in the art is a self-locking rivet type fastener that includes a pre-lock configuration in which the shank is readily inserted into a hole, with minimal insertion pressure. What is further needed is a self-locking type rivet fastener that expands automatically as part of the insertion process, and that is locked into place upon full insertion. Further what is needed is a releasable type rivet fastener easily used and securely positioned, yet releasable for removal and re-use.
The present invention provides a rivet-type fastener for securing within a hole of a work piece. The structure of the fastener causes automatic expansion of the fastener as the fastener is inserted in the hole, and engages locking members to secure the fastener in the hole.
In one aspect thereof, the invention provides a fastener for a work piece with a base and first and second arms attached to the base and extending outwardly therefrom. The first and second arms each include proximal segments and distal segments conjoined at ends thereof. A post extends inwardly between the arms, from the conjoined distal segments toward the base. The arms and the post have cooperating structures for spreading the arms and locking the arms in a spread position, as relative axial movement occurs between the arms and the post.
In another aspect of the invention, a fastener is provided with a base having a surface defining a channel, and opposed arms joined to the base in spaced relation on opposite sides of the channel. The arms include distal segments. A post is joined to the distal segments of the arms and extends between the arms towards the base. The post includes a transverse bar between the arms and aligned with the channel. Lateral protrusions extend outwardly from the post, and have tips. Notches in the arms engage the tips of the lateral protrusions in a locked position.
In still another aspect thereof, the invention provides a rivet-style fastener with a base having a,surface defining a channel. First and second opposed arms are joined to the surface of the base, in spaced relation to each other, and on opposite sides of the channel. The arms include relatively thicker proximal segments and relatively thinner distal segments. A post is joined to the distal segments and extends between the arms towards the base. The post includes a transverse bar between the arms and aligned with the channel. The bar has a length greater than the width of the hole. Lateral protrusions extend outwardly from the post, and have wedge surfaces ending at protrusion tips. Notches are provided in the proximal segments for engaging the tips of the lateral protrusions. Ramp surfaces on the arms direct the tips from the unlocked position to a locked position in which the tips are engaged by the notches, and the arms are deflected outwardly.
An advantage of the present invention is providing a unitary rivet-style fastener, with automatic locking structures activated upon insertion of the fastener in a work piece.
Another advantage of the present invention is providing a fastener for a hole in a work piece that locks during insertion and can be unlocked for removal and re-use.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings in which like numerals are used to designate like features.